Multicenter, randomized, double-blind, placebo-controlled study to evaluate the efficacy & safety of topical acyclovir (5%) cream vs. placebo cream in treatment of herpes labialis lesions in immunocompetent subjects initiating treatment after the beginning of the next herpes labialis episode. Time to healing for classical lesions (time from vesicle formation until loss of hard crust) and lesion "abortion" (ie, episode does not progress beyond papular stage [no vesicle form]) will be examined as secondary variable. Other secondary measures will include pain, tenderness, viral shedding.